Every cylinder head reconditioned by HM GEM goes through a stringent cleaning and inspection process prior to machining. Cylinder head are firstly dismantled chemically or sonically cleaned and visual checked for suitability for re-use. Non-destructive magnetic particle crack testing is the first step before then measuring or critical areas.
All components are checked including valve guide bores, valve masking heights, and valve margins. Parts, including inlet and exhaust valves, retainers, springs, and washers are also checked for serviceability.
The machining process includes valve guide replacement and reaming, valve facing, valve seat replacing and cutting all to the original Equipment Manufacturers specifications. The fire deck is milled and where required fire rings are recut. The casting is pressure tested to ensure no internal flaws or porosity is evident.
On completion of the machining process the cylinder head is hot soap washed and prepared for finally assembly. Final checks includes valve to seat bluing, vacuum testing and record finished valve masking heights.